Every year, thousands of migrants attempt the hazardous journey by boat from North Africa to Europe. Many don't make it. The tragedy over the weekend where up to 900 people drowned trying to make that crossing is contributing to the growing call to confront the migration crisis. Our colleague Renee Montagne spoke with the U.N.'s special rapporteur, or independent expert, on the human rights crisis.

RENEE MONTAGNE, BYLINE: And that man, Francois Crepeau, blames Syria's four-years long civil war for fueling much of the migration that's led to disasters at sea. For many, this exhausting journey begins not at sea but far inland.